Babies are born with the instinct to suckle milk from their mother's breasts, but it is often necessary for them to drink liquids from other sources. It is common throughout the world to feed liquids to babies in nursing bottles, also known as baby bottles. A nursing bottle is used by filling cylindrical container with liquid, securing a flexible nipple to the open end of the container, inverting the bottle, and placing the nipple into the baby's mouth. The baby then sucks on the nipple to drink the liquid. None of these nursing bottles completely solves the problem of maintaining the interior of the bottle at atmospheric pressure while preventing leaks and spills. They also do not provide a simple user-friendly system for mothers. Accordingly, a demand still exists for a nursing bottle, which prevents the formation of a partial vacuum inside the bottle during nursing yet does not result in spills, and is simple to use.